1. Field of the Invention
The present invention relates to carbon film coated glass which is applicable, for instance, to repellent glass, a reactor, such as a reactor pipe and so on, or the like.
2. Description of the Related Art
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 188,447/1990, carbon film coated glass, which is utilized, for example, as a reactor pipe, has been known. This conventional carbon film coated glass comprises quartz glass and a carbon film which is formed on a surface of the quarts glass. The carbon film coated glass is produced by supplying a carried gas which includes a raw material adapted for forming a carbon film onto the surface of the quartz glass. The quartz glass has been reduced with a hydrogen gas in advance.
The conventional carbon film coated glass, however, has drawbacks in that the adhesion between the carbon film and the quartz glass is insufficient, and in that the carbon film is likely to come off accordingly. Hence, the conventional carbon film coated glass has been lacking durability. In addition, the conventional carbon film coated glass sometimes suffers from insufficient repellency in certain applications.
A first aspect of the present invention has been developed in view of the drawbacks of the conventional carbon film coated glass. It is an object of the first aspect of the present invention to provide carbon film coated glass whose carbon film is less likely to come off.
Further, a second aspect of the present invention has been developed also in view of the drawbacks of the conventional carbon film coated glass. It is an object of the second aspect of the present invention to provide carbon film coated glass whose repellency is held to a sufficient extent and at the same time whose carbon film is less likely to come off.
The first aspect of carbon film coated glass according to the present invention comprises:
a glass substrate; PA1 an intermediate layer formed on a surface of the glass substrate in a thickness of 50 angstroms or more and including metallic oxide in an amount of 5% or more by mole and balance of carbon at least; and PA1 a carbon film formed on a surface of the intermediate layer in a thickness of 10 angstroms or more. PA1 a glass substrate; PA1 an intermediate layer formed on a surface of the glass substrate in a thickness of 50 angstroms or more and including metallic oxide in an amount of 5% or more by mole and balance of carbon at least; and PA1 a fluorine-including carbon film formed on a surface of the intermediate layer in a thickness of 10 angstroms or more and combined with fluorine in a surface thereof at least.
Further, the second aspect of carbon film coated glass according to the present invention comprises:
As the glass substrate, it is possible to employ a glass substrate which includes oxide glass such as silicate glass, borosilicate glass, soda-lime glass, flint glass, or the like. This glass substrate can be in a variety of shapes such as a plate-like shape, a pipe-like shape, and so on.
As the metallic oxide of the intermediate layer, it is possible to employ one or more of the following metallic oxides: SiO.sub.2, TiO.sub.2, ZrO.sub.2, Y.sub.2 O.sub.3, Al.sub.2 O.sub.3, PbO, CaO, MgO, B.sub.2 O.sub.3, Fe.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, and so on. This intermediate layer includes the metallic oxide in an amount of 5% or more by mole. When the intermediate layer includes the metallic oxide in an amount of less than 5% by mole, the adhesion between the glass substrate and the intermediate layer, and the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film are insufficient. Here, the amount can be derived from the mole fraction which expresses a composition of a material mixture. Namely, the mole fraction is the ratio of the number of moles of a component in a material mixture to the total number moles of all the components in the material mixture, and accordingly the sum of the moles fractions of all the components in the material mixture is 1 (i.e., 100% by mole). This mole fraction can be calculated as follows. For instance, let the present intermediate layer which includes the carbon and the metallic oxide be a material mixture. When the atomic percentage (or atomic %) of either one the carbon and the metallic oxide is known, the mole fraction of the other component can be derived therefrom. Further, let the present fluorine-including carbon film be a material mixture. When the atomic % of either one the carbon and the fluorine is known, the mole fraction of the other component can be derived therefrom.
As the intermediate layer, it is possible to employ an intermediate layer which includes the metallic oxide and balance of carbon. Further, it is preferred to employ an intermediate layer which includes the metallic oxide, fluorine and balance of carbon, since such a construction further gives repellency which results from the fluorine even after the carbon film or the fluorine-including carbon film is worn out. Furthermore, in order to further improve the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film, it is preferred to employ an intermediate layer in which the atomic % of the carbon increases with respect to that of the metallic oxide as the intermediate layer approaches the outermost surface.
This intermediate layer is formed on a surface of the glass substrate in a thickness of 50 angstroms or more. When the thickness of the intermediate layer is less than 50 angstroms, the adhesion between the glass substrate and the intermediate layer, and the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film is insufficient, and accordingly such a thickness adversely affects the repellency, for instance.
This intermediate layer can be formed by physical vacuum deposition (hereinafter abbreviated to PVD), chemical vacuum deposition (hereinafter abbreviated to CVD), or the like. In particular, it is preferred to form the intermediate layer by PVD in view of the adhesion improvement.
In the first aspect of the carbon film coated glass according to the present invention, the carbon film includes carbon at least. In the second aspect of the carbon film coated glass according to the present invention, the fluorine-including carbon film includes a carbon film which is combined with fluorine in its surface at least. The carbon film and the fluorine-including carbon film are formed on a surface of the intermediate layer in a thickness of 10 angstroms or more. When the thickness of the carbon film and the fluorine-including carbon film is less than 10 angstroms, the carbon included in the carbon film and the fluorine-including carbon film is less likely to effect its functions such as the wear resistance or the like.
The carbon film and the fluorine-including carbon film can be formed by PVD, CVD, or the like. In particular, it is preferred to form the carbon film and the fluorine-including carbon film by PVD in view of the adhesion improvement. The fluorine-including carbon film can be formed by PVD in which a gas containing fluorine, such as a CF.sub.4 gas or the like, is employed. In this way, a surface fluorination treatment can be carried out during PVD. In the case that PVD is employed, the intermediate layer and the carbon film or the fluorine-including carbon film can be formed continuously by adapting the metallic oxide and the carbon to be targets or evaporation sources and by varying sputtering electric power or the like as time elapses. When the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by radio frequency (hereinafter abbreviated to RF) sputtering, RF electric power is varied. Further, when the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by PVD, electron beam (hereinafter abbreviated to EB) current or resistance heating current is varied. Furthermore, when the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by direct current (hereinafter abbreviated to DC) sputtering, DC current is varied.
In the carbon film coated glass according to the present invention, micro-fine convexes and concaves which result from the carbon particles deposited on the surface shed water or the like which is present or the surface, and thereby the water or the like is made into droplets because of the surface tension. Thus, the present carbon film coated glass repels the water or the like. Accordingly, the present carbon film coated glass can be adapted to be repellent glass which is applicable to automobile windshield glass or the like. If such an application is desired, the carbon film coated glass is adapted to be transparent repel lent glass by employing the following construction. Namely, if such is the case, a transparent glass substrate is employed, the kind of the metallic oxide to be employed is selected, the mole percentages of the metallic oxide and the carbon in the intermediate layer and the carbon film or the fluorine-including carbon film are adjusted, and the thicknesses of the intermediate layer and the carbon film or the fluorine-including carbon film are adjusted so that the present carbon film coated glass exhibits a predetermined transparency. Moreover, the present carbon film coated glass can be adapted to be a reactor pipe or the like into which a gas or the like is introduced and the gas or the like is reacted with carbon or the like.
In the first aspect of the carbon film coated glass according to the present invention, since there is provided the intermediate layer between the glass substrate and the carbon film and since the intermediate layer adheres closely to the glass substrate and the carbon film, the intermediate layer works as a binder layer which binds the glass substrate and the carbon film together. Therefore, it is believed that the intermediate layer inhibits the carbon film from coming off.
Further, in the second aspect of the carbon film coated glass according to the present invention, since the fluorine-including carbon film is employed which is combined with fluorine in its surface at least, the repellency can be improved. Likewise, in the second aspect of the carbon film coated glass, since there is provided the intermediate layer between the glass substrate and the fluorine-including carbon film and since the intermediate layer adheres closely to the glass substrate and the fluorine-including carbon film, not only the intermediate layer keeps the improved water repellency, but also it inhibits the fluorine-including carbon film from coming off, as described above.
In particular, when the intermediate layer is formed by PVD or CVD, the metal atoms and the carbon atoms are activated during the vapor deposition process so that metal-carbon (M-C) bonds are more likely to form between the metal atoms and the carbon atoms. As a result, a firmer intermediate layer can be formed.
As having been described so far, in the first and second aspects of the carbon film coated glass according to the present invention, since there is provided the intermediate layer between the glass substrate and the carbon film or the fluorine-including carbon film, the carbon film or the fluorine-including carbon film is less likely to come off.
Especially, in the second aspect of the carbon film coated glass according to the present invention, the fluorine-including carbon film is employed which is combined with fluorine in its surface at least, the carbon film coated glass can be improved in the repellency.
Since the present carbon film coated glass has an excellent durability as described above, repellent glass, a reactor pipe, or the like, to which the present carbon film coated glass is applied, can be used for a long period of time.